[flashrom] [PATCH] Check availability of GPO lines on Intel PIIX4

[Michael Karcher]

Am Sonntag, den 15.08.2010, 01:00 +0200 schrieb Mattias Mattsson:
> This patch changes the intel_piix4_gpo_set() function to always check
> the GENCFG and XBCS registers for the availability of the
> requested GPO line before raising/lowering it and fails otherwise. It
> makes no attempt to bypass the values in these configuration
> registers.
Please mark all board enables using intel_piix4_gpo_set() untested then,
because we don't know whether the reconfiguration to output is needed.
It shouldn't be that much.

> The old flashrom code did consider it safe to reprogram (multiplexed)
> GPO:s 22-26 without checking the value of the controlling register
> (GENCFG). I do not really know why.
Probably because vendor BIOS board enables (which have been reverse
engineered to make the flashrom code) uses boilerplate code that makes a
pin GPO and sets it at the same time.

> Signed-off-by: Mattias Mattsson <vitplister at gmail.com>
One question remaining: Why do you think GPO8 is "never available". The
only special behaviour about GPO8 I could find in the data sheet is that
GPO8 has a defined low level in standby mode, but it should work as
usual in all other modes. Otherwise the patch looks great. I verified
the table against the datasheet, looks correct.

Thanks for your work,
  Michael Karcher